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From: "Pascal J. Bourguignon" <pjb@informatimago.com>
To: help-gnu-emacs@gnu.org
Subject: Re: How to delete all nil properties from a plist?
Date: Sun, 02 Aug 2015 03:36:22 +0200	[thread overview]
Message-ID: <871tfmv5d5.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: mailman.7753.1438479312.904.help-gnu-emacs@gnu.org

Emanuel Berg <embe8573@student.uu.se> writes:

> Marcin Borkowski <mbork@mbork.pl> writes:
>
>>> Hi all, so I'm still using plists, though I'm less
>>> and less sure that they are actually better than
>>> alists for my use-case. Now I need to delete all
>>> properties whose value is nil. I'm using this
>>> function:
>
> Try this:
>
> (require 'cl)
>
> (defun plist-drop-nil-props (l)
>   (let((new)
>        (prop nil) )
>     (cl-loop for x in l
>              do (if (or (setq prop (not prop)) x)
>                     (setq new (append new (list x)))
>                   (setq new (butlast new))))
>     new))

This is horrible. Again, you can't prevent yourself writing O(n²) code
when O(n) would do perfectly.




-- 
__Pascal Bourguignon__                 http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk


  parent reply	other threads:[~2015-08-02  1:36 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-01 22:03 How to delete all nil properties from a plist? Marcin Borkowski
2015-08-01 22:11 ` Marcin Borkowski
2015-08-02  1:32   ` Emanuel Berg
     [not found]   ` <mailman.7753.1438479312.904.help-gnu-emacs@gnu.org>
2015-08-02  1:36     ` Pascal J. Bourguignon [this message]
2015-08-02  1:50       ` Emanuel Berg
2015-08-02  3:55       ` Rusi
2015-08-02 16:21         ` Pascal J. Bourguignon
     [not found]       ` <mailman.7754.1438480361.904.help-gnu-emacs@gnu.org>
2015-08-02 16:24         ` Pascal J. Bourguignon
2015-08-05 23:08           ` Emanuel Berg
     [not found]           ` <mailman.7864.1438816202.904.help-gnu-emacs@gnu.org>
2015-08-05 23:30             ` Pascal J. Bourguignon
2015-08-05 23:49               ` Emanuel Berg
2015-08-06  0:30               ` Emanuel Berg
2015-08-06  1:05                 ` John Mastro
2015-08-06  1:07                   ` John Mastro
     [not found]               ` <mailman.7867.1438818687.904.help-gnu-emacs@gnu.org>
2015-08-06  2:32                 ` Pascal J. Bourguignon
2015-08-07 22:21                   ` Emanuel Berg
     [not found]               ` <mailman.7869.1438821124.904.help-gnu-emacs@gnu.org>
2015-08-06  2:40                 ` Pascal J. Bourguignon
2015-08-07 22:32                   ` Emanuel Berg
     [not found]                   ` <mailman.7963.1438986782.904.help-gnu-emacs@gnu.org>
2015-08-08  3:56                     ` Pascal J. Bourguignon
2015-08-09  1:34                       ` Emanuel Berg
     [not found]                       ` <mailman.7996.1439084206.904.help-gnu-emacs@gnu.org>
2015-08-09  2:18                         ` Pascal J. Bourguignon
2015-08-09  2:28                           ` Emanuel Berg
     [not found] ` <mailman.7749.1438467076.904.help-gnu-emacs@gnu.org>
2015-08-01 23:46   ` Pascal J. Bourguignon
     [not found] <mailman.7748.1438466648.904.help-gnu-emacs@gnu.org>
2015-08-01 23:43 ` Pascal J. Bourguignon

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